1. Field of the Invention
This invention relates to an insulation cap being put on a wire joint formed by joining cores of a plurality of covered wires and insulation cover near the wire joint, and a joined electrical wire using the insulation cap.
2. Description of the Related Art
An example of the insulation cap to be put on the wire joint of a plurality of covered wires and insulation cover near the wire joint is fixed with the covered wire by winding a tape around them. FIG. 15 shows an example of such insulation caps (refer patent document 1).
An insulation cap 50 shown in FIG. 15 includes a cap main body 51, which a wire joint 54 joining cores 53b together and insulation cover near the wire joint are inserted into, and a support plate 52 projecting from an opening edge of the cap main body 51 for fixing the covered wire. The cap main body 51 has an opening at one end and a closed end at the other end. The wire joint 54 is inserted through the opening as an insertion end, and sealant 56 is filled therethrough. Covered wires 53 are fixed on the support plate 52 with a tape 55 for preventing the wire joint 54 from falling out from the cap main body 51.
According to the insulation cap 50 by prior art, it is not assured that the inserted wire joint 54 is positioned at the center of cap main body 51. Therefore, the insulation cap 50 is fixed by curing the sealant 56 in a condition of the wire joint 54 positioned with a tilt. In that case, the sealant 56 is not filled in every corner so that the wire joint 54 is filled unevenly around it with the sealant 56 and the wire joint 54 does not have enough waterproofness.
FIG. 16 shows another example of insulation cap 60 by prior art, of which a wire joint 67 is positioned in the center (reference document 2). The insulation cap 60 has an opening at one end and a closed end at the other end as same as the insulation cap 50. A wire joint 67 is formed by joining cores 65b and an electro-conductive sleeve 66 together. The insulation cap 60 is formed into a stepped cylindrical shape. An insulation cover 65a near the wire joint 67 is covered by a large diameter part 61, and the wire joint 67 is received in a small diameter part 64 continued to the large diameter part 61. The large diameter part 61 is provided at an opening edge 62 with a flexible fastener 63 to be folded toward an inside of the insulation cap 60 around a base formed as an integral part of the opening edge 62.
The wire joint 67 is inserted while bending the flexible fastener 63. After the wire joint 67 is inserted completely, a top end of the flexible fastener 63 restored elastically to an initial position engages with a rear end of the sleeve 66 of the wire joint 67. Thereby, the wire joint 67 is prevented from falling out from the opening edge 62.
Patent references are follows;
Reference 1: Japan Patent Application No. H10-243539,
Reference 2: Japan Patent Application No. H8-22847.
Objects To Be Solved
However, a length of the flexible fastener 63 of the insulation cap 60 is short and the flexible fastener 63 is located near the opening edge 62 of the insulation cap 60. Thereby, the wire joint 67 is not received deeply in the insulation cap 60 so that a wire element of the core is exposed from the opening edge 62 and water comes into the insulation cap. Therefore, the wire joint 67 has poor waterproofness.
Even if the insulation cap 60 is made of a transparent or semitransparent resin, the wire joint 67 is located near the large diameter part 61 of the insulation cap 60. Therefore, a gap between the wire joint 67 and the insulation cap 60 is large to see difficultly inside the insulation cap 60. It cannot be confirmed from outside of the insulation cap 60 that the wire joint 67 is inserted into a predetermined position so that failures of fastening or waterproofing the wire joint 67 possibly occurs. When the wire joint 67 is inserted and a sealant for waterproofing is filled into the insulation cap 60, the sealant covers around the wire joint 67 and it becomes more difficult to see the wire joint 67.